Polyester compositions

Abstract

The invention relates to compositions comprising polyethylene terephthalate (PET), poly(1,4-cyclohexanedimethanol terephthalate) (PCT) and titanium dioxide, to the use of these compositions for production of products resistant to heat distortion for short periods, and to a process for producing polyester-based products resistant to heat distortion for short periods, preferably electric or electronic polyester-based products, especially polyester-based optoelectronic products.

What is claimed is: 
     
         1 . Compositions comprising
 a) 3% to 30% by weight of poly(1,4-cycohexylenedimethylene) terephthalate (PCT), where the proportion of PCT based on the sum total of all the themoplastic polymers present in the composition is in the range from 5% to 40% by weight,   b) 15% to 90% by weight of polyethylene terephthalate (PET) and   c) 7% to 70% by weight of titanium dioxide, where the individual components should be combined with one another
 in such a way that the sum total of al the percentages by weight is 100. 
   
     
     
         2 . Compositions according to  claim 1 , characterized in that the titanium dioxide for use as component c) has a median particle size (d50) in the range from 90 nm to 2000 nm. 
     
     
         3 . Compositions according to  claim 1 , characterized in that they comprise, in addition to components a), b) and c), also d) 5% to 50% by weight of glass fibres, in which case the level of at least one of components a), b) and c) should be reduced to such an extent that the sum total of all the percentages by weight is 100. 
     
     
         4 . Compositions according to  claim 3 , characterized in that component d) is cut long glass fibres having a starting length in the range from 1 to 50 mm. 
     
     
         5 . Compositions according to  claim 3 , characterized in that component d) has a fibre diameter in the range from 7 to 18 μm. 
     
     
         6 . Compositions according to  claim 3 , characterized in that they comprise, in addition to components a), b), c) and optionally d) or instead of d), also e) 0.01% to 15% by weight of talc, in which case the level of at least one of the other components should be reduced to such an extent that the sum total of all the percentages by weight is always 100. 
     
     
         7 . Compositions according to  claim 6 , characterized in that microcrystalline talc having a median particle size d50 in the range from 0.5 to 10 μm is used. 
     
     
         8 . Compositions according to  claim 6 , characterized in that they comprise, in addition to components a), b), c) and optionally d) and/or e) or instead of components d) and/or e), also f) 0.01% to 1% by weight of at least one phosphite stabilizer, in which case the level of at least one of the other components should be reduced to such an extent that the sum total of all the percentages by weight is 100. 
     
     
         9 . Compositions according to  claim 8 , characterized in that the phosphite stabilizer used is at least one selected from the group of tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythrityl diphosphite, bis(2,6-dl-tert-butyl-4-methylphenyl)pentaerythrityl diphosphite, bis(2,4-dicumylphenyl)pentaerythrityl diphosphite, tris(nonylphenyl)phosphite, (2,4,6-tri-t-butylphenol)-2-butyl-2-ethyl-1,3-propanediol phosphite and tetrakis(2,4-di-tert-butylphenyl)-1,1-biphenyl-4,4′-diyl bisphosphonite. 
     
     
         10 . Compositions according to  claim 9 , characterized in that the phosphite stabilizer used is at least tetrakis(2,4-di-tert-butylphenyl)-1,1-biphenyl-4,4′-diyl bisphosphoite. 
     
     
         11 . Compositions according to  claim 8 , characterized in that they comprise, in addition to components a), b), c) and optionally d) and/or e) and/or f) or instead of components d) and/or e) and/or f), also g) 0.01% to 15% by weight of at least one demoulding agent, in which case the level of at least one of the other components should be reduced to such an extent that the sum total of all the percentages by weight is 100. 
     
     
         12 . Compositions according to  claim 11 , characterized in that the demoulding agent used is at least one from the group of ester wax(es), pentaerythrityl tetrastearate (PETS), long-chain fatty acids, salt(s) of the long-chain fatty acids, amide derivative(s) of the long-chain fatty acids, montan waxes and low molecular weight polyethylene or polypropylene wax(es), and ethylene homopolymer wax(es). 
     
     
         13 . Compositions according to  claim 12 , characterized in that long-chain fatty acids used are stearic acid or behenic acid, salts of long-chain fatty acids used are calcium stearate or zinc stearate, the amide derivative of long-chain fatty acids used is ethylenebisstearylamide, and montan waxes used are mixtures of straight-chain, saturated carboxylic acids having chain lengths of 28 to 32 carbon atoms. 
     
     
         14 . Products obtainable by extrusion or injection moulding of moulding compositions comprising the compositions according to  claim 1 . 
     
     
         15 . Process for producing products resistant to heat distortion for short periods, characterized in that compositions according to  claim 1  are processed as matrix material in the form of thermoplastic moulding compositions in an injection moulding or extrusion operation.